I just got myself a Yamaha CP-60M, and I really like this electric piano.
It has a few issues, and I’m hoping to get some advice.
There is sound coming out of the effects loop, Send A.
The midi also works.
The issues:
No sound out of the Send B of the effects loop. And no sound out of the left and right outputs.
The sliders and buttons on the piano are not doing anything, but the lights do work on the buttons.
The piano has piezo pickups that are placed at different parts of the piano. The treble side of the keyboard seems to be at half volume compared to the middle, and bass side.
I have ordered some Deoxit fader cleaner, and some deoxit fader grease. I thought it would be a good first try at getting the control panel working.
I’m wondering if anyone has worked on something like this before or have some general advice. I’m wondering how repairable 80s Yamaha electronics are?
Here are some pictures of the piano. Not the best quality, but if it would help I can take better pictures. I’m away from home this weekend.
Can’t help you with this, I’m afraid, but just wanted to say that these pianos are very cool, and it’s nice to see you amplifying it with current Yamaha gear! Good luck…
Looking at the block diagram it looks like you could have an issue with the FX loop switching. If you’re getting signal at send a but not send B that would indicate something around the switching. I’ve no idea if they’re mechanical switches, relays or solid state switches but I’d be having a close look around that area first. If there is an issue with switch A or B then that would explain why the signal can’t get to the GEQ section and also why there’s nothing at send B jack. I’ve not seen the schematics to boil the theory down any further
If the switch is mechanical it shouldn’t be too hard to find out if it’s got continuity through it, likewise for a relay. Most prob using a 4016/4066 analogue switch or similar if it’s solid state switching. For that or a relay circuit make sure the control side is working correctly. Again, could just be something like a 4013 flip flop not flipping or flopping!
Of course there’s the possibility that the return jack of loop A is bad? If the switch is in the on position the FX jacks become an insert point meaning you need to return the signal back from the last pedal to the piano!
It’s all just hypothetical but something between the control board and the sound board burnt out, that’s why part of the keybed is half dead receiving low voltage. also sliders and buttons as well as the line level output being dead supports the hypothesis fwiw. deoxit isn’t going to fix this.
nice piano though, should be fun when it’s up and running.
Fault finding takes patience, a methodical approach and it’s not uncommon to have several faults or at least some faults to present themselves after you’ve repaired the first fault! I’d try and work one stage at a time if I were you. You know you’ve got a signal of sorts present at the FX send so use that as your start point. Try and get that signal through to the output jack then you can focus on the differing levels across the keyboard. I doubt the two are related (but I can’t say for sure without looking at the schematics). It’s tempting to want to dive into repair all the issues you see at first hand but there’s always cause and effect to factor in (fault 1 could have a bearing on fault 2 for example) hence the methodical step by step approach.
Referring back to the block diagram the electronics that you’re having issues with doesn’t look like it should be too challenging. You’ve got an EQ section that you can hard bypass with a switch, a tremolo circuit and LFO and a final buffer stage. Following the signal path from the FX switching should show up where the signal disappears. All good advice from @jukka but try to focus on logical steps. In other words I wouldn’t re cap any boards until I was fairly sure I had faulty caps. Whilst it’s true they dry out over time and some fail I’ve got plenty of 70’s and 80’s gear still rocking their original caps without issue. In fact it might just be me but I’ve found more failed diodes and less so op amps in gear of that vintage? Connectors, jack sockets, switches etc and easily checked (and eliminated) and a thorough visual inspection is always a good idea.
Thank you for the supportive comments everyone, and the diagram @Bunker
I was able to dig a bit into the piano today. I found the amp board was easy to access. It wasn’t obvious where, but I did find how to access the control panel circuit. I ran out of time, so I’ll have to try to actually open it another day to get a good look.
Also, I found that if I plug into the effects B send and hold the button down for effects loop A, I get sound through the B send. Seems to need to be held down to work, even when it seems like it should be on from clicking the button on.
I also studied the piezo pickups for awhile. I found out from this post on Ep-forum that in parts they are connected by “pressed” connections, instead of soldered. I have read that they have a history of failure in the pressed connection points.
I am confident I can fix these if it’s just some soldering.
Well at least we know fom the look of things the caps on the amp aren’t blown, good for you for taking initiative also. Hope it all works out in short order!
If there is a connection problem with a button you could unplug the pigtail from the button that is the culprit and plug it into the other button, if it works then the button (in that case) probably has gone south. The buttons themselves should be the same, there are 2 correct? A and B?
That video should be a big help, looks like a nice quality instrument inside as well. should be great when it’s up and thumping. I think once it’s open, with a screwdriver you can remove the board from the face and then try the working button on the non working side, you may even find that the button is just out of alignment or there’s a prong inside that can be bent back to make it work again.
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